Get rid of getStride()

It was confusing and not properly used everywhere.
Callers should use the stride they get when they get
the buffer pointer.
diff --git a/unix/x0vncserver/XPixelBuffer.cxx b/unix/x0vncserver/XPixelBuffer.cxx
index f88eda4..f464182 100644
--- a/unix/x0vncserver/XPixelBuffer.cxx
+++ b/unix/x0vncserver/XPixelBuffer.cxx
@@ -35,8 +35,7 @@
     m_dpy(dpy),
     m_image(factory.newImage(dpy, rect.width(), rect.height())),
     m_offsetLeft(rect.tl.x),
-    m_offsetTop(rect.tl.y),
-    m_stride(0)
+    m_offsetTop(rect.tl.y)
 {
   // Fill in the PixelFormat structure of the parent class.
   format = PixelFormat(m_image->xim->bits_per_pixel,
@@ -57,7 +56,7 @@
 
   // Calculate the distance in pixels between two subsequent scan
   // lines of the framebuffer. This may differ from image width.
-  m_stride = m_image->xim->bytes_per_line * 8 / m_image->xim->bits_per_pixel;
+  stride = m_image->xim->bytes_per_line * 8 / m_image->xim->bits_per_pixel;
 
   // Get initial screen image from the X display.
   m_image->get(DefaultRootWindow(m_dpy), m_offsetLeft, m_offsetTop);